<form name="myForm" action="<{:U('Wap/Bxalipay/pay')}>" method=post>
<input type="hidden" name="WIDout_trade_no" value="<{$order_no}>" />
<input type="hidden" name="WIDsubject" value="<{$WIDsubject}>" />
<input type="hidden" name="WIDtotal_fee" value="<{$WIDtotal_fee}>" />
</form>
<script>
document.forms["myForm"].submit();
</script>